A conventional power generator includes an armature having wire conductor coiled around an iron core and rotatably mounted between two poles of a magnet, with a pair of brushes which rotatably rub a pair of slip rings connected to two ends of the armature for collecting alternating current as produced from the generator; or with a pair of brushes which rotatably contact a commutator consisting of two insulated segments for collecting direct current from the generator.
However, the conventional power generator may have the following drawbacks:
1. When rotating the armature by an external driving force, a partial driving force will be required to overcome the magnetic force between the iron core and the poles of the magnet, thereby consuming input energy for rotating the armature of the conventional power generator. PA1 2. The brushes are rotatably contacted with the slip rings or commutator, thereby producing frictional heat and decreasing the current collection efficiency. PA1 3. The emf of the power generator depends upon the rotating speed, the number of coil windings and the flux density so that a faster rotation of a densely coiled armature between the magnetic poles within a closed generator housing may produce much heat which requires effective cooling for dissipating heat outwardly. Otherwise, the accumulation of heat may influence a smooth operation of the generator and may shorten its service life.